<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>Both divs should be part of opaque layers.</title>

<style>

.content {
  box-sizing: border-box;
  width: 200px;
  height: 200px;
  border: 1px solid black;
  margin: 10px;
}

.relative {
  position: relative;
}

.fixed {
  position: fixed;
  top: 140px;
  left: 140px;
}

.low-z {
  z-index: 1;
}

.high-z {
  z-index: 2;
}

.opaque-background {
  background-color: white;
}

body {
  height: 4000px;
}

</style>

<div class="content relative low-z" reftest-assigned-layer="page-background"></div>

<div class="fixed opaque-background content high-z" reftest-assigned-layer="fixed-layer"></div>

<div class="content relative low-z" reftest-assigned-layer="page-background"></div>
